# Terra (classic) smart contract implementation notes

This folder contains documents that describe various implementation aspects of the Terra smart contracts. Where appropriate, we also discuss historical context and the rationale behind certain design decisions.

- [Token ID encoding in the Token bridge](token_id.md) describes the token ID scheme used by the Token Bridge contract.
- [Upgrading the CW20 wrapped token contract](token_upgrades.md) describes the Token Bridge contract and its implementation.


